New study shows DNA less likely to predict disease than previously thought

Lifestyle choices and environmental impacts may be better at predicting disease than genetic tests.

As far back as recorded history, human beings have been looking for ways to cure and avoid disease. Now that we are in the age of medical science, and the advent of antibiotics and vaccines have reduced the chance of dying from many common diseases to effectively zero, researchers have been looking at preventable diseases like cancer and heart disease.

For the last decade, much hope has been staked upon the possibilities of DNA sequencing, whereby an individual's propensity for life-threatening disease could be determined and then potentially avoided by changing environment, lifestyle or prescribing drugs. It was thought that if heart problems and cancers could be predicted (or at least anticipated), that we would all be able to live longer, healthier lives. Unfortunately, it looks like the promise of individual DNA analysis for the most common diseases isn't as useful as was hoped.

A new study has found that, as the New York Times reports, "While sequencing the entire DNA of individuals is proving fantastically useful in understanding diseases and finding new treatments, it is not a method that will, for the most part, predict a person’s medical future."

The study looked at the medical records of 53,666 identical twins from around the world, and found that even for those with some genetic predisposition for certain diseases, the resulting probability of their actually getting the disease was similar to that of the general population.

“Even if you know everything about genetics, prediction will remain probabilistic and not deterministic. I am a big believer in randomness,” said Dr. David Altshuler, professor of genetics and medicine at Harvard Medical School.

Turns out that randomness, environment and behavior play a scale-tipping role.

While this isn't good news for the future of this kind of medicine, it is good fodder for healthy-lifestyle proponents and environmentalists. The most interesting part of the New York Times' coverage was left unsaid — a clean and healthy community, an active lifestyle and responsible eating, incorporating lots of plants and little or no meat (a diet that has been previously proven to lower cancer rates and heart disease) can, over large populations, have a greater effect than DNA sequencing (and these are a lot less expensive and invasive).

While DNA research should continue, and that perhaps these results could be reversed, it seems that when we are thinking about public policy, and how best to protect our families and ourselves, the key lies in the preventable measures that we already know reduce disease risk.